Aqueous-based inorganic–organic hybrid coating materials comprising self-assembled silica nanophase (SNAP) particles and the sodium salt of 9,10-anthraquinone-2,6-disulfonate (AQDS), an oxygen-scavenging precursor molecule, were coated onto PET films under ambient laboratory conditions using a spiral-bar coating technique. Active SNAP-based coatings containing 0.08% w/w AQDS displayed an oxygen transmission rate of 0.04 ± 0.01 cm³ mil m⁻² day⁻¹ atm⁻¹; an improvement in oxygen barrier by an order of magnitude compared with comparable coatings produced using dip-coating. The spiral-bar coating technique also provided other important technical advantages over the previously used dip-coating method, including a reduction in the AQDS concentration required in the coating solution by almost an order of magnitude. The oxygen barrier performance provided by these single-layer active SNAP-based coatings approaches that provided by other far more sophisticated multi-layer plastic barrier materials produced using vacuum-deposition methods.